A variety of exercise devices including treadmills, cycles, stair climbers and other devices are known in the art and generally fall into two categories, motor driven and operator driven. In those devices incorporating motor driven technology, the operator induces certain shock loads on the operating system. For example, during the operation of a treadmill, as the operators foot impacts the moving belt a momentary stoppage of the belt occurs caused by the developed friction generated by the sudden download forces increasing the friction between the moving belts' undersurface and the treadmills stationary sliding surface. As a result, two undesirable loading forces occur, the first being mechanical and the second being electrical. These adverse mechanical forces are applied against the entire drive mechanism, the moving belt itself, the underlying sliding surface, the gears, pulleys, belts, drive mechanism, the driving motor and its bearings and even the motor mounting support structure.
Likewise, increased electrical current loads are induced in the entire electrical system, including wiring, components, and motors. As a result, the wiring must be oversized to accommodate the increased current, all switches and components must be oversized and the electrical motor itself must be oversized to avoid motor stall during peak torque demands. A leveling of the load in the typical installation, that is, averaging out peak and steady state loads, allows a reduction in the size of the electric motor and related components by approximately forty percent. This reduction can be seen in prior devices such as treadmills where the moving belt is suspended thereby limiting impact frictional forces.
Likewise, adverse mechanical load forces effect the entire structure of the exercise device. The belt must be stronger to absorb additional forces, gears and pulley mechanisms must be heavier, the bearings and motor support brackets must be larger and stronger. Devices such as stair climbers also incur mechanical and electrical shock loads during operation. As an operator steps from one pedal to another during stair climber operation, impact forces cause torsional forces to be applied throughout the drive mechanism, through the drive motor to the frame of the exerciser. These forces result in severe stresses on the motor support brackets leading to metal fatigue and cracking. In fact, the peak impact loads are transmitted through the entire mechanism thereby requiring larger electrical components and larger mechanical components.
Because of the expense of these oversized components and of the potential mechanical failure of the exercisers, various methods and techniques have been used to reduce or eliminate shock loads. These methods and techniques include providing motor-to-exerciser connections that can absorb some of the shock, such as using a pulley-drivebelt assembly to connect the driving motor to the exerciser operating component. Additionally, considerable prior art development has been accomplished in the area of reducing frictional effects on treadmill devices. In the stair stepper devices, some prior art devices have incorporated small spring devices at the pedal attachment points in order to provide a small amount of give at the pedal. None of these methods have been wholly satisfactory, and as a result, overdesign and oversizing of components is still required.